Method for producing a high strength concrete

ABSTRACT

A high strength concrete is produced under such condition that the concrete is left to stand under atmosphere and a sufficient curing can not be effected by adding calcium sulfoaluminate hydrate-forming minerals to concrete materials in such a small amount that the concrete does not expand.

AU 115 EX Kitsuta et al.

[ 1 Aug. 26, 1975 Kagaku Kogyo Kabushiki Kaisha, both of Tokyo, Japan Filed: Sept. 27, 1973 Appl. No.: 401,299

Foreign Application Priority Data Sept. 27, 1972 Japan 47-96750 US. Cl. 106/89; 106/90; 106/314 Int. Cl. C048 7/02 Field of Search 106/89, 90, 314

References Cited UNITED STATES PATENTS 11/1964 Klein 106/89 3,251,701 5/1966 Klein l06/89 3,303,037 2/1967 Klein 106/89 3,359,225 l2/l967 Wcisend 106/89 3,510,326 5/1970 Miki 106/89 3,628,973 12/1971 Greening et a1. 106/89 3,663,287 5/1972 Mizunuma et a1. 106/90 3,666,515 5/1972 Nakagawa 106/89 3,677,780 7/1972 Nishi et al 106/90 Primary Examiner-J. Poer Attorney, Agent, or Firm-Sughrue, Rothwell. Mion, Zinn and Macpeak [57] ABSTRACT A high strength concrete is produced under such condition that the concrete is left to stand under atmosphere and a sufficient curing can not be effected by adding calcium sulfoaluminate hydrate-forming minerals to concrete materials in such a small amount that q the concrete does not expand.

6 Claims, 3 Drawing Figures PATENTEU Auczsms SHEET 1 OF 3 0 0 0 W w m 6 5 4 w w Age (hour) PAIENIEB 3, 90 1 ,722

SHEET 3 0f 3 j; x/O

3' 200- U Q Q. 5 I00 (I) 3 v 24 68/0/2/4/6 Amount of cement add/five (Based on Parr/and cement) METHOD FOR PRODUCING A HIGH STRENGTH CONCRETE The present invention relates to a method for producing a concrete having a high strength even by leaving to stand under atmosphere and a high freezing and thawing resistance. When a concrete has a high strength, the necessary cross-sectional area becomes smaller and consequently the weight of the structure is decreased and the working cost is reduced.

A high strength concrete can be obtained when the curing can be fully conducted as in a curing in steam or a curing in water but. when a concrete is cast in place as in a prestressed concrete bridge. the curing cannot be conducted satisfactorily and in general the concrete is exposed to atmosphere. ln this case the strength is -307: lower than the strength when the curing is effected in water. The high strength concrete which is exposed to atmosphere and cannot be subjected to the curing in water. considerably reduces the freezing and thawing resistance and where the concrete is always exposed to a cold weather, the strength is hardly developed and the durability is low.

The present invention solves these defects and provides a method for producing a concrete showing a compression strength at an age of 28 days of more than 800 Kg/cm even by leaving to stand under atmosphere and having an excellent freezing and thawing resistance.

The present invention comprises the production of a high strength concrete under such a condition that the concrete is allowed to stand under atmosphere and a sufficient curing cannot be effected. which is characterized in that calcium sulfoaluminate hydrate-forming mineral powders are added to concrete materials in such a small amount range that the concrete does not expand. It has been known that the presence of calcium sulfoaluminate hydrate-forming minerals compensates the shrinkage of concrete by utilizing the expansion energy generated in the hydration, but in this process it is impossible to increase the compression strength at an age of 28 days to more than 800 Kglcm The present invention enables to increase the strength of concrete and improve the freezing and thawing resistance by making the calcium sulfoaluminate hydrate-forming minerals present in concrete in such an amount that the concrete does not expand and therefore the present invention is different in the technical idea from the conventional method wherein the shrinkage of concrete is compensated by utilizing the expansion energy.

The calcium sulfoaluminate hydrate-forming minerals to be used in the present invention include the following substances and the item (1) is the most effective.

l. A mixture of a crystalline or amorphous calcium aluminate, such as CA. C A, CA C A C A CaF and C A .CaF and gypsum or a product obtained by simultaneously burning the calcium aluminate-forming materials and gypsum can be used. A mixture of an amorphous product of C A or C, A .CaF and gypsum is preferred. The weight ratio of calcium aluminate to gypsum is l:0.5l0. preferably 1:0.8-5.

2. C A -gypsum. The weight ratio of C A S to gypsum is l:0.2-2, preferably l:0.4-1.0.

3. Alumina containing slag-gypsum.

In any case. when Frec-CaO is not contained. the improvement of strength is high and effective. In the above descriptions. C means CaO. A means A1 0 and S means S0 The amount of these minerals is the range within which the concrete does not expand when the expansion percentage is determined but for cement the amount is 243% by weight, preferably 4-87! by weight.

The fineness in Blaine value is not less than 3.000 em /g. preferably 4.000-8.000 em /g.

In less than 3,000 cm'-/g. the function for promoting the hydration of cement considerably lowers and the unreacted product remains for a long period of timeand the stability is poor. while when the Blaine value exceeds 8.000 cm /g. the hydration is too rapid in some minerals and the false setting occurs.

The present invention is characterized in that the calcium sulfoaluminate hydrate-forming mineral powders are compounded in cement in an amount of 2-l 3% by weight. the unit cement amount (an amount of cement required for the formation of l m concrete) is 500-700 Kg, a water/cement ratio is 18-35%, and 0.3-57r by weight based on cement. of a surfactant is added while blending concrete. The unit cement amount of 500-700 Kg is essential for the production of the high strength concrete and further is a necessary I requirement for developing a high freezing and thawing resistance. When the unit cement amount is less than 500 Kg, even if the calcium sulfoaluminate hydrateforming minerals are added in such a range that the concrete does not expand. it is impossible to increase the compression strength at an age of 28 days to more than 800 Kg/cm and the freezing and thawing resistance cannot be improved.

When the unit cement amount exceeds 700 Kg, the strength is not improved in proportion to the increased amount and rather Young's modulus decreases and the heat amount of hydration is too much.

The cement to be used in the present -invention includes Portland series cement, mixed cement and the like.

When the water/cement ratio exceeds 35%. it is impossible to increase the compression strength at an age of 28 days to more than 800 Kg/cm while when said ratio is less than 18%, even if a surfactant is used, it is impossible to blend a concrete having a workability tory workability is obtained in a low unit water amount and for the purpose, at least one of surfactants selected from the group consisting of anionic sulfonate, a sulfuric acid ester salt. non-ionic polyhydric alcohols, a condensate of naphthalenesulfonate with formalin, ethylene oxide addition product and non-ionic anionic surfactants is added in an amount of 0.3-5% by weight based on cement during blending the concrete. Among them, anionic sulfonate is the most effective.

The coarse aggregate to be simultaneously blended must have a strength of at least L000 Kg/em and the fine aggregate ratio is used in an amount of 20-50% by weight.

The concrete produced under such conditions has a compression strength at an age of 28 days of more than 800 Kg/cm only by leaving to stand under atmosphere and the creep properties and the compression fatigue properties are favorable and the seawater resistance and the freezing and thawing resistance are high.

The freezing and thawing resistance is a required property to give the high strength of more than 800 fig/cm" to the cast-in-place concrete. which is always exposed to a cold weather and the concrete using tt conventional AE agent cannot develop such a high tem and the free waterhaving a relation to the freezing and thawingis contained as a verystable water of crysf tallizationandadense structure can he obtained.

As mentioned above, the concrete obtained in the method of'the present invention, even if the curing which is heretofore and generally needed; is not con The pr'esentinvention will he explained tail. For a better understanding of the invention. refer- -in more dc ence is taken to the accompanying drawings. wherein:

FIG. 1 is a viewshowing a relation of thc hydration percentage of the cement samples to the age (hours) through an X-ray diffraction process;

FIG. 2 is views of X-ray diffraction of the cement additivcs to he used'in the present invention: and

ducted, has a compression strengthof more than 800 Kg/cm" at an age of 28 days andfurther the freezing -a'nd thawing resistance is high and therefore the present invention is useful for the concreting in site at a cold weather place. J

In order to make the content'ofthe present invention more clear, an explanation will be made with respectto the result of X-ray diffraction fora cement paste pre pared'under the same conditions 'as in Example l.

.FlG. l is a View showing a relation of the hydration percentage of cement to the age.

In the measurement, a high-earlystrength cement is used, water/cement ratio is 30% and 1% by weight based on cement, of an anionic sulfonate surfactant (made by KAO SOAP K.K.. Trade Mark: Mighty 150) is added thereto and the resulting cement paste is cured in water or air and an amount of unhydrated alit is determined by X-ray diffraction with respect to each sample and calculated into the hydration percentage.

Both the curves 1 and 2 show the result of samples in which the calcium sulfoaluminate hydrate-forming minerals are not added and the curve 1 shows the sample of curing in air and the curve 2 shows the sample of curing in water.

The curves '3 and 4 show the result of the cement paste added with the calcium sulfoaluminate hydrateforming minerals prepared in Examplejl and the curve 3 shows the sample of curing in air and the curve 4 .ance and the like.

3 components as shown in Table l werc'used as the start ing materials l4L47r by'weight of quick lime. l 7.0% by g FIG. 3 is a view showing a relation of the expansion percentage determined by 11S Mortal to the amount of the cement additive added.

The following examples are given for the purpose of illustration of this invention and are not intended as limitations thereof.

a lnExamplel; the calciumsulfoaluniinate hydrate I forming minerals consisting mainly of "C, A CaC O (referred to as cement additi e A" hereinafter) and C A CaSO (referred to 'as (cement additive hereinafter) are added.

Examples 2 and 3 show the tests in which the experimerits were effected by adding the cement additive A and at. a low temperature. a Q

I a 7 EXAMPLE l Quick lime bauxiteand gypsum having the chemical weightof bauxite and,68.6% by weight of gypsum were compounded and 5% by weight offluorite was added I J t i thereto and the resulting mixture was fused in an elec tric furance. The melt at a temperature of 1,29 0"C was taken out in a mold and gradually cooled and then pulverized (cement additive A).

The same melt was blown into air and quenched and pulverized (cement additive B).

The cement additive A consists mainly of C A and CaSO and the cement additive B consists mainly of A5 and CaSO The chemical analytical value of these additives is shown in Table 2 and the X-ray diffraction views of these minerals are shown in FIG. 2.

These cement additives were pulverized into a Blaine value of 5,500 cmlg and each of the thus pulverized cement additives was added to high-early-strength Portland cement in an amount of 016% by weight based on the cement. A mortarhaving a weight ratio of each of the mixed cements and sand being l:2 was prepared into a sample of 4X4Xl6 cm. The thus formed sample was determined with respect to the variation of length (expansion percentage) by a comparator (following to MS R5201, .llS All24) and the result is shown in FIG. 3. ln FIG. 3, thecurve 1 shows the result of the sample using the additive A and the curve 2 shows the result of the sample using the additive B.

Table 1 Chemical component ('71) Component Ignition Starting loss M 0 CaO SO, SiO: mo Others Total material Quick lime O.l 0.5 95.7 0.2 0.4 1.9 0.8 99.6

Bauxite 0.3 86.2 g (1.3 3.9 55 3.4 99.6

Gypsum Table 2 Chemical component of cement additive.

. Insoluble Component component A1. .0; (.aO S; 510: F0203 Others By using the cement additive A. a concrete test was effected. The physical properties and the chemical components of the concrete material are shown in Tables 3. 4. and 6.

Table 3 Physical properties of high-early-strength Portland cement.

Fineness Setting Strength (Kg/cm") Specific Blaine 88;; Water lnitial Final Bending Compression gravity value residue amount (cmlg) W (71) hr. min. hr.min. 1 day 7 days 28 days 1 day 7 days 28 days 3.12 4.390 0.4 28.6 2 32 3 27 35.7 67.3 78.4 136 355 453 Table 4 Chemical component and various factors of high-early-strength Portland cement. ignition Insoluble SiO, A1 0,, Fc O CaO MgO SO: F-CaO Total SM 1M HM loss component Table 5 Physical properties of aggregate. Percentage passed through screen (71) Water Unit Fineness Specific absorbed amount 25 20 15 5 2.5 1.2 0.6 0.3 0.15 modulus gravity amount (Kg/m) mm mm mm mm mm mm mm mm mm mm '71 Himegawa crushed 100 22.4 42.2 6.54 2.65 0.99 1.602

stone Liver 100 90.6 69.0 42.2 18.6 4.2 2.75 2.63 1.52 1.695 sand W Table 6 amount of ater The slump was ad usted to 12-15 cm. Rock Q b 45 The result of the strength test of the concrete is (Kg/cm) shown tn Table 7. Himcgflwfl The samples of Experiment Nos. 6, 11 and shot'v crushed h b I 11 1'1 1 h stone Granite. Andesite. Sand stone 1.500 2.500 t e expanslon m t e at er p t c expanslon was not observed.

The concrete compounding is shown in the following Table 7. The unit Portland cement amounts were 450, 500, 600 and 700 Kg and the cement additive was added in an amount of 0-15'7c by weight based on 50 Experiment Nos. 2, 3, 4. 5, 8, 9, 10, 13 and 14 are the method of the present invention.

With respect to the cement additive B, the same test was made and substantially the same result was obtained.

Table 7 Concrete compounding Curing in water Curing in air (C) Fine aggre- Water/ Actually Expcr Cement gate cement Com- Commeasured iment Cement additive ratio ratio pression Bending pression Bending slump No. (Kg/m) (Kg/m") 1 (70 1) (Kg/cm) (Kg/cm) (Kglcm (Kg/cm) (cm) Table 7-continucd Concrete compounding Curing in water (uring in air Fine , aggri. Water Auto-all Exper- Cement gate cement Com- Commeasured imcnt Cement additive ratio ratio pression Bending Pressiun Bending slump No. (Kg/m") (Kg/m) ('70 t) VJ) (Kg/em t (Kg/cm) (Kg/em) (Kg/em t (cm) EXAMPLE 2 EXAMPLE 3 By using the cement additive A prepared in Example 1 and the high-early-strength Portland cement in Table 4. a concrete test at a low temperature of 5C was made. The concrete compounding rate was shown in the following Table 8 but the other was the same as in Example 1.

By using the cement additive A prepared in Example 1. the high strength concretcs having a compression strength of more than 800 Kg/cm" (an age of 28 days) were prepared in the recipe of Table IOQFor the comparison. the result of the commercially available highearly-strength Portland cement (Experiment No. 21 is Table 8 Concrete compounding a Fine I Fine Coarse Exper- Water/cement aggregate Cement aggregate aggregate Mighty Cement iment ratio ratio 5121 amount Water amount amount 150 additive No. (7H (Kg/m) I (Kg/m) (Kg/m) (Kg/m") Kg/m") (Kg/m) 17 28.8 34 550 g i 15s 586 1.158 8.25 0 18 29.1 34 550 160 g 565 1.152 8.25 22 I9 29.4 34 550 162 5 1.149 8.25 33 in any of the Experiment Nos. the slump was 181:2 cm and the temperature was adjusted by ice water. The

shown together. The other materials were same as in Example 2. The addition ratio of Mighty 150 is based result of the strength test is shown in the following 40 on the cement.

Table 10 Concrete Compounding Coarse Fine Unit amount (Kg/m) Experaggregate Water/ aggreiment maximum cement gate Cement Fine Coarse Mighty Air N0. size ratio ratio Cement additive Water aggreaggre- 150 Slump amount (mm) ('1) ('1) A gate gate (71) (cm) (71) Table 9 but this is an average value of three samples of l5 50 em and the curing was effected by leaving to stand the samples in a chamber at 5C under a humidity of The samples did not expand.

Table 9 Compression strength Experiment Compression strength No. (Kg/cm) 7 days 2X days For the measurement of the dynamic modulus of elasticity and the strength, the samples of 7.5X10X10 5 cm and l0d 20 cm were molded respectively and the Table l 1 Result of the freezing and thawing test in strength Start of lixper- Strength freezing Freezing and thawing cycle number DF iment at age and value No. 01'28 days thawing i) (Kg/em) (age of 14 days) 50 70 100 150 Table 12 Result of the freezing and thawing test in dynamic modulus of elasticity Start of freezing Freezing and thawing cycle number Experand DF iment thawing value Nov (age of 2) 14 days) 10 20 3O 50 70 100 150 (Kg/cm Z0 6.72Xl0 6.72Xl0" 6.60X10" 6.56Xl0 613x10 SfaOXlO" 4.5OX10" 0.ll()Xl()" 16.0 (100) (100) (95.0) (93.1) (83.2) (69.5) (45.0) (19.9) 21 67BX10 601x10" 511x10" 224x10 01BX10" 2.6

What is claimed is:

l. A method for producing a high compressive strength concrete having a high freezing and thawing resistance under the condition that the concrete is left to stand under atmosphere and a sufficient curing can not be effected. which comprises blending 2-13% by weight based on cement of (A) a mixture of l2CaO.- 7Al O not containing free-CaO and gypsum or (B) a product not containing free-CaO obtained by simultaneously burning a material to form l2CaO. 7Al O and gypsum, to Portland cement in a unit cement amount of 500 700 Kg and a water cement ratio of 18 the weight ratio of l2CaO. 7Al O to gypsum being 1108-5, the fineness in Blaine value of the l2CaO. 7A1- 0;, being 4,000 8,000 cm lg.

2. A method as claimed in claim 1, wherein 0.35% by weight based on cement of at least one of surfactants selected from the group consisting of an anionic suifonate, sulfuric acid ester salts, a non-ionic polyhydric alcoho]. a condensate of naphthalenesulfonate and formalin, an ethylene oxide addition product and a nonionic anionic surfactant is added thereto.

3. The method as claimed in claim 1, wherein the amount of (A) or (B) is 4-87: by weight.

4. The method of claim 1 wherein said blended concrete is concreted on site and has a compression strength at an age of 28 days of more than 800 Kg/cm.

5. A method as claimed in claim 4, wherein 03-57: by weight based on cement of at least one of surfactants selected from the group consisting of an anionic sulfonate, sulfuric acid ester salts. a nonionic polyhydric alcohol, a condensate of naphthalenesulfonate and formalin, an ethylene oxide addition product and a nonionic anionic surfactant is added thereto.

6. The method of claim 1 wherein the l2CaO. 7Al O- has an amorphous form. 

1. A METHOD FOR PRODUCING A HIGH COMPRESSIVE STRENGTH CONCRETE HAVING A HIGH FREEZING AND THAWING RESISTANCE UNDER THE CONDITION THAT THE CONCRETE IS LEFT TO STAND UNDER ATMOSPHERE AND A SUFFICENT CURING CAN NOT BE EFFECTED, WHICH COMPRISES BLENDING 2-13% BY WEIGHT BASED ON CEMENT OF (A) A MIXTURE OF 12CAO. 7AL2O3 NOT CONTAINING FREE-CAO AND GYPSUM OR (B) A PRODUCT NOT CONTAING FREE-CAO OBTAINED BY SIMULTANEOUSLY BURNING A MATERIAL TO FORM 12CAO. 7AL2O3 AND GYPSUM, TO PORTLAND CEMENT IN A UNIT CENENT AMOUNT OF 500 - 700 KG AND A WATER CEMENT RATIO OF 18-35%, THE WEIGHT RATIO OF 12CAO. 7A12O3 TO GYPSUM BEING 1:0,8-5, THE FINENESS IN BLAINE VALUE OF THE 12CAO. 7A12O3 BEING 4,000-8,000 CM2/G.
 2. A method as claimed in claim 1, wherein 0.3-5% by weight based on cement of at least one of surfactants selected from the group consisting of an anionic sulfonate, sulfuric acid ester salts, a non-ionic polyhydric alcohol, a condensate of naphthalenesulfonate and formalin, an ethylene oxide addition product and a non-ionic anionic surfactant is added thereto.
 3. The method as claimed in claim 1, wherein the amount of (A) or (B) is 4-8% by weight.
 4. The method of claim 1 wherein said blended concrete is concreted on site and has a compression strength at an age of 28 days of more than 800 Kg/cm2.
 5. A method as claimed in claim 4, wherein 0.3-5% by weight based on cement of at least one of surfactants selected from the group consisting of an anionic sulfonate, sulfuric acid ester salts, a nonionic polyhydric alcohol, a condensate of naphthalenesulfonate and formalin, an ethylene oxide addition product and a non-ionic anionic surfactant is added thereto.
 6. The method of claim 1 wherein the 12CaO. 7Al2O3 has an amorphous form. 